Various deodorizing methods have been suggested to eliminate environmental or industrial odors resulting from the work place, toilets, refrigerators, refuse bins, etc. The following methods are given as examples of these conventional deodorizing methods: (i) use of the odor-masking effect of an aroma, (ii) adsorption using a porous inorganic material, such as activated carbon, as a deodorant, (iii) odor-elimination by a chemical reaction of an adsorbent whose main component is citric acid or maleic acid, (iv) deodorizing with ozone, and (v) deodorizing with a deodorant whose raw materials are vitamin C and a ferrous sulfate.
However, such conventional deodorizing methods have the following problems. According to method (i), the odor is not essentially eliminated. In method (ii), the adsorption capability of the deodorant is limited, so that its adsorptivity decreases early. Method (iii) is available for adsorbing ammonia, amine, etc., but cannot be used for eliminating mercaptans. Since method (iv) uses an oxidizer, a secondary pollutant is produced. The deodorant according to method (v) is very susceptible and sensitive to temperature variations.
Moreover, a conventional deodorant prepared by immersing a simple inorganic carrier in a catalytic solution of a noble metal such as Ni, Pt, Ru, Rh, Ag, Co, or Ir, has a somewhat greater deodorizing effect and is useful for eliminating mercaptans. However, since sulfur molecules generated during decomposition of the mercaptan bond strongly to the noble metal, the catalytic activity of the noble metal is lowered over time. Moreover, regeneration of the deodorant by heating is difficult.